Steam generator



Feb. 9, 1943.

D. H. N. MAYO ETAL 2,310,801

STEAM GENERATOR Filed July 16. 1958 4 Sheeqs-Sheet 1 Fig] Dana'HJV ArhurE/Payzzar ATTORNEY.

I Feb. 9, 1943. D. H. N. MAYO ETAL 2,310,801

STEAM GENERATOR Filed July 16, 1938 4 Sheets-Sheet 2 INVENTORS DanaH/VMayo' 4 I Ari/7:11 Zi/Paynor ATTORNEY;

1943- D. H. N. MAYO ETAL 2,310,801

STEAM GENERATOR Filed July 16, 1938 4 Sheets-Sheet 3 INVENTORS Dana HNMayo 2w Ari/var E. Eayna'z" ATTORNEY.

Feb. 9, 1943. D. H. N; MAYO ETAL STEAM GENERATOR Filed July 16, 1938 4sheets-s eet 4 IN VENTORS TQ v x? W S SJHJH S 3 SA C Qn O ,r 0 O O A O Ho H O J L /o 4 O L L1 4 4 O Dana IVA/Mayo 2 d 1 12f hurEEaynor ATTORNEY.

Patented Feb. 9, 1943 UNITED STATES PATENT OFFICE STEAM GENERATOR Dana11. N. Mayo, Ridgewood, N. 1., and Arthur E. Raynor, Rockville Centre,N. Y., assignors to The Babcock a Wilcox Company, Newark, N. 1., acorporation of N ew Jersey Application July 16, 1938, Serial No. 219,562

13 Claims.

iliary water heating, 1. e. economizer surface.

The main object of the invention is the provision of an improvedarrangement and constructlon of the economizer in a steam generator ofthe character described which is characterized by the simplicity andeffectiveness of the'economizer surface supporting provisions, theaccessibility of the economizer surface for renewal and inspection, theprotection of the by-pass control parts from overheating, and the highthermal efllciency of the steam generator unit with the by-pass in orout of use.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which wehave illustrated and described a preferred embodimentof the invention.

Of the drawings:

Fig.1 is a partly diagrammatic sectional elevation of a steam generatingunit incorporating the invention;

Fig. 2 is an enlarged view of an upper portion Fig. 11 is a verticalsection taken on the line I I-l l of Fig. 10.

In the drawings the invention is illustrated as incorporated in a steamgenerator-of the Babcock & Wilcox high head type comprising a two-stagepulverized coal burning furnace having a primary section III and asecondary section II. The

primary furnace section It is defined by fully studded tube wallsdesigned for the maintenance therein of a normal mean furnacetemperature above the ash fusion temperature of the coal used. nozzlesI2 are arranged to downwardly discharge through the arch l3 of theprimary section. A

: water cooled floor I4 is constructed to collect and support a layer ofmolten slag in the primary section Hi which is withdrawable therefromthrough a slag tap opening IS in one of the side walls adjacent thefloor level. The primary fur Fig. 7 is a plan view of the structureshown in Fig. 6;

Fig. 8 is a vertical section taken'on the line 8-8 of Fig. 6;

Fig. 9 is a vertical section taken on the line 99 of Fig. 2;

Fig. 10 is an enlarged view of -a portion of Fig. 2; and

nace section is partly'separated from the secondary section by a fluidcooled partition it formed by refractory covered fully studded watertubes having their'lower portions bent out of the plane of the tube rowto form a series of transversely spaced gas passages l'l connecting theprimary and secondary furnace sections.

The secondary furnace section II is of conthe boiler circulation systemhereinafter de'-'-"" scribed.

The convection heated pressure parts of the unit comprise a bank ofsteeply inclined steam generating tubes 20 extending between rows ofvertical uptake and supply headers 2| and 22 respectively. Thelowermostrow of tubes 20 exheaders 2| and a horizontal cross header 2!arranged below and connected to the supply headers 22 by nipples 24.Alternate tubes in this row are bent differently to form a slag screento protect the remaining portion of the bank. A steam and water drum 25is arranged transversely of and at a substantial distance above the tubebank A plurality of pulverized coal burning 22. A row of circulatortubes 26 starting at the top of the uptake headers 2| connects them tothe steam space of the drum 25, while another row of circulator tubes 21connects the water space-of the drum to the cross header 23. Another rowof tubes 26 extends vertically from the upper end of the supply headers22 into a cross header 29 which is connected to the steam space of thedrum 25 by tubes 30. The intertube spaces of the row of tubes 28 andnipples 24 are closed by refractory material to define a vertical bailiestructure 3i forming with the row of supply headers 22 a continuation ofthe front side of the secondary furnace section to the header 29. Thevertical portions of the downtake circulator tubes 21 also have theirintertube spaces closed by refractory to define a wall 32 parallel tothe baflle wall 3i.

With the described construction the space enclosed by the tube bank 20,uptake circulators 2'6, drum 25, and downtake clrculators 21 is dividedby the baiiie structure 3| into an upflow section 35, the sides of whichform an extension of the secondary furnace section sides, and a downfiowsection 36 between the battle 3| and the wall 32, the downflow sectionbeing substantially wholly at the front side of the headers 22. Aninclined refractory baiile 31 extends downwardly from the lower portionof the baiiie structure 3| in a plane spaced from the lower end ofthewall 32 to provide a heating gas exit from the lower end of thedownflow section 36 to an external air heater and stack connection. Theportions of some of the circulator tubes 21 extending across the gasexit are bent out of a single row to provide space for the gas exit.

The portion of the setting occupied by the gas upflow and downflowsections is of substantial volume and advantageously employed for thelocation of the convection heated auxiliary fluid heating surface of theunit. The auxiliary fluid heating surface comprises serially connectedvertically spaced banks of multiple-looped horizontally arrangedsuperheater tubes 40 arranged in flat coils extending betweensuperheater inlet and outlet headers 4| and 42 respectively, with thetube coils vertically arranged and extending from the uptake circulatortubes 26 to a point rearwardly of the tube row 28. The space between theforward ends of the superheater coils and the bafile structure3l isemployed as an upflow by-pass passage 35a for controlling the heatabsorption of the superheater tubes as hereinafter described. A row oftubes 44 extends inwardly and upwardly from the upper level of thesupply headers 22 adjacent the forward. ends of the superheater tubecoils to a transverse header 45 arranged parallel to and spaced from theheader 29. Tubes 46 extend vertically from the header 45 and thenlaterally to the steam space of the drum 25. The portions of the tubes44 opposite the superheater tube coils have their intertube spacesclosed by refractory to define a vertical baffle 41 extending from theheader 45 to a point below the superheater tube bank and forming therear side of the gas by-pass passa e 35a and separating it from the mainup-pass 35.

Steam generating units of the character described are designed for theproduction of high pressure superheated steam with steam temperaturesapproximately 950 F. at the superheater outlet header. The attainment ofsuperheated steam temperatures of this value necessitates the presenceof high temperature heating gases 'in contact with the superheater tubeswith consequent special problems of supporting and protecting the partsin this section of the unit. The by-pass passage 36a permits the amountof heating gases contacting with the superheater to be regulated. Forthis purpose one or more by-pass dampers 66 are movably mounted on theheader 45 and arranged to extend over the top of the passage 36a to theheader 29. The' dampers 56 are externally operable in any suitablemanner to control the amount of heating gases passing through theby-pass and consequently the amount passing over the superheatersurface. To preserve the high thermal efficiency of the unit when theby-pass is in operation and also to prevent the control dampers 50 frombecoming overheated, a pair of vertically spaced economiz- .er sectionsand 52 are positioned in the bypass passage. Each of these economizersections consists of a bank of vertical flat coils of multiple-loopednested horizontal tubes arranged sideby-side and extending transverselyof the tube bank 20, and as shown in Fig. 9, corresponding coils of thesections are serially connected. The lower ends of the tubes in thesection 5! are connected to an external inlet header 53, while the upperends of the tubes in the section 52 are connected to an external outletheader 54, which in turn is connected to the water space of the drum 25.The arrangement of the economizer sections transversely of the tube bankpermits the tube coils to be readily inspected and renewed throughaccess openings in the side walls of the setting and simplifies themaintenance of the sections. It also permits the headers to be outsideof the setting which would not be practicable otherwise.

The gas downflow section 36 contains the main economizer divided intothree superposed vertically spaced sections 60, 6 I, and 62, each ofwhich is formed by a series of horizontally extending multiple-loopedvertical flat tube coils arranged side-by-side and extending in adirection transversely of the tube bank 20. Corresponding tube coils ofadjacent banks are connected as hereinafter described for a serial flowof water successively through the sections 60, 6|. and 62 in the ordernamed. The lower ends of the tubes in the section 60 are connected to anexternal inlet header 63, while the upper ends of the tube coils in thesection 62 are connected to an external outlet header 64. Tubes 65connect the header 64 to the inlet header 53 of the by-pass economizersections. With this arrangement of countercurrent flow of water relativeto the heating gas flow is provided through the economizer sections 60,6i, and 62, with a parallel flow through the by-pass economizer sections5| and 52 in the order named but in both the water flow is generallyupward. A counter-current flow through the economizer sections 60, 6i,and 62 is advantageous from the standpoint of thermal efllciency, whilea parallel flow through the by-pass economizer sections 5! and 52 isadvantageous in preventing the tube coils in that section from becomingsteam-bound when steam is generated therein.

The described convection heated pressure parts are top supported fromthe external steel framework of the unit by means of U-shaped straps 66surrounding the drum 25 and hangers 61 welded to the tubes 30, 46 and26. The economizer sections 66, BI and 62 are supported as shown inFigs. 2 to 'I. The tubes of the section 66 are centrally supported frombelow on an I-beam 'Ifl which extends between and is carried by a pairof I-beams ll extending through the side walls of the setting to theexternal steel work. The tube legs above the beam Ill are rigidlyconnected and supported from below by spacer members 12 welded toadjacent tube legs. The economizer section 60 is also supported frombelow at its opposite ends from the side walls of the setting, as shownin Figs. 6 to 8. The lowermost' loop of each coil has a hook-shapedbracket 13 welded thereon and engaging a rod or bar 14 resting on spacedbracket members 15 welded at spaced points to a vertically extendingchannel member' 16 incorporated in the corresponding side of thesetting. The superjacent loops are supported from the bottom loop bydove-tail spacer connections 11, as shown in Figs. 6 and 8. Similarprovisions are used for supporting the ends of the sections BI and 62from the sides of the settime.

The upper economizer sections BI and 62 are centrally supported frombelow by the section 50 by the interconnecting tube portions, as shownin Figs. 4 and 5. The tube ends to be connected are joined by a coupling18 and connected by slip hangers to the adjacent horizontally extendingtubelegs. Each slip hanger consists of an inner U-shaped lug l9 weldedonto the curved portion of the tube and fitting around a pin 80removably mounted in a pair of outer U-shaped lugs 8| welded onto thestraight tube portion. With this arrangement the superjacent tube coilsare centrally supported by tube portions acting as short columns undercompression. The economizer supporting provisions described eifectivelymaintain the economizer sections in their desired position, whilepermitting the looped ends of eachtube coil to expand and contract as a.whole relative to the end supports and independent] of one another.

Special fluid cooled supports are provided for the by-pass economizersections and 52. As shown, each section is centrally supported frombelow by a group of tubes 85 extending at a slight inclination from acorresponding horizontally arranged header 86 at the front side of thewall 32 inwardly between the main economizer sections to a point beyondthe tube row 44 turning upwardly parallel to the tubes 44 and 46 andthen horizontally along the top of the setting to the steam space of thedrum 25. The lower horizontal portions of the tubes 85 are supported onlugs 81 carried by the tubes 29 and 44, as shown in Figs. and 11. Theportions of the tubes 85 directly below each economizer tube coil areprovided with tube supporting blocks 88 welded thereon on which thelowermost legs of the economizer section rest. The upper horizontal legsof the economizer tube coils are supported centrally from the lowermostleg by spacer blocks I2 similar to the spacers for the main economizersections. Similar supporting tubes 89 are arranged to support the loopedend portions of each economizer section. Superjacent looped portions ofthe economizer tubes are interconnected to one another by dove-tailedspacer blocks, as shown in Fig. 8. Each of the headers 85 is connectedto the water space of the drum by tubes 90 to provide a fluidcirculation through the corresponding supporting tubes 85 and 89.Support hangers 9| are connected to the upper ends of the verticalportions of the tubes 85 and 89 to transmit the load thereon to theexternal supporting steel work.

As shown in Figs 2 and 0 the forward end of each superheater tube coilhas an expansible of each coil will be free to expand and contractsupporting connection to the supporting tubes 44, 85, or 89. Each tubecoil carries on its uppermost loop a hook member 93 engaging a bar 94mounted on brackets 95 carried by adjacent supporting tubes. A similararrangement is used at the opposite end of each superheater tube coilfor expansibly supporting that end from the up take circulator tubes 26.The subjacent tube legs of each superheater coil section are expansiblysupported from the superiacent tube legs by slip hangers of the typeshown in Fig. 5. With the described arrangement the superheater tubeloops closing a bank of inclined steam generating tubes,

an elevated steam and water drum, rows of uptake and downtake.circulator tubes connecting the opposite ends of said tube bank to saiddrum, means forming bailles dividing the space defined by 'said tubebank, circulator tube rows and drum into a plurality of gas passesincluding a plurality of upflow passes above said steam generating bankand a downflow pass serially connected to said upflow passes at theirupper ends and arranged beyond the downtake endof said steam generatingbank, a bank of steam heating tubes extending across and confined to oneof said upflow passes, a sectional economizer comprising a tube bankextending across only said downfiow. pass and a second tube bankserially connected thereto and extending across only the other upflowpass, flow control damper means for the last named upflow pass arrangedabove said second economizer tube bank, said economizer tube banks beingarranged with the tubes thereof extending transversely of said' steamgenerating tube bank, and means for supporting said economizer tubebanks.

2. A steam generator comprising a setting enclosing a bank of inclinedsteam generating tubes, an elevated steam and water drum, rows of uptakeand downtake circulator tubes connecting the opposite ends of said tubebank to said drum. means forming baflles dividing the space defined bysaid tube bank, circulator tube rows and drum into a plurality of gaspasses including a wide upflow pass above the uptake end of said steamgenerating bank. a narrow upflow pass above the downtake end of saidsteam generating bank, and a downflow pass serially connected to saidupflow passes at their upper ends and arranged laterally adjoining saidnarrow upflow pass beyond the downtake end of said steam generatingbank, a bank of steam heating tubes extending second tube bank seriallyconnected thereto and extending across only said narrow upflow-pass,flow control damper means for said narrow upflow pass arranged abovesaid second economizer tube bank, said economizer tube bankbeingarranged with the tubes thereof extending transversely of said steamgenerating tube bank, and means for supporting said economizer tubebanks.

3. A steam generator comprising a setting enclosing a bank of inclinedsteam generating tubes, a steam and water drum arranged a substantialdistance above said tube bank, rows of uptake and downtake circulatortubes connecting the opposite ends of said tube bank to said drum,longitudinally spaced rows of vertically disposed fluid conduit elementshaving their lower ends connected to the lower end of said tube bank andtheir upper ends to said drum, means associated with said elementsforming baflles dividing the space defined by said tube bank, circulatortube rows and drum into a' plurality of gas passes including a wideupflow pass above the uptake end of said steam generating bank, a narrowupflow pass above the downtake end of said steam generating bank, and adownflow pass serially connected to said upflow passes at' their upperends and arranged laterally adJoining said narrow upflow pass beyond thedowntake end of said steam generating bank, a bank or steam heatingtubes extending across and confined to said wide upflow pass, asectional economizer comprising a tube bank extending across only saiddownflow pass and a second tube bank serially connected thereto andextending across only said narrow upflow pass, fiow control damper meansfor said narrow upflow pass arranged above said second economizer tubebank,.

said economizer tube banks being arranged with the tubes thereofextending transversely of said steam generating tube bank and said steamheating tube bank, and means for supporting said economizer tube banks.

, 4. A steam generator comprising a setting enclosing a bank of inclinedsteam generating tubes, an elevated steam and water drum, rows of uptakeand downtake circulator tubes connecting the uptake and downtake ends ofsaid tube bank respectively to said drum, means dividing the spacedefined by said tube bank, circulator tube rows and drum into aplurality of gas passes including a pair of upflow passes, a bank ofsteam heating tubes extending across one of said upfiow passes, fiowcontrol damper means for the other upflow pass, an economizer tube bankin said other upflow pass below said damper means with the tubes thereofarranged transversely oi said steam generating tube bank, and

a plurality 01 supporting tubes extending across said other upflow passbelow and supporting said economizer tube bank.

5. A steam generator comprising a setting enclosing a bank or inclinedsteam generating tubes, an elevated steam and water drum, rows of uptakeand downtake circulator tubes connecting the uptake and downtake ends ofsaid tube, bank respective to said drum, means forming baiiles dividingthe space defined by said tube bank, circulator tube rows and drum intoa plurality of gas passes including a pair or upflow passes and alaterally adjoining downflow pass serially connected to said upflowpasses at their upper ends, a bank of steam heating tubes extendingacross one of said upfiow passes, fiow control damper means for theother upflow pass, an economizer tube bank in said other upflow passbelow said damper means with the pass and said other upflow pass belowand sup porting said economizer tube bank and having their opposite endsconnected to said drum.

6. A steam generator comprising a setting enclosing a bank of inclinedsteam generating tubes, a steam and water drum arranged a substantialdistance above said tube bank, rows 01 uptake and downtake circulatortubes connecting the uptake and downtake ends or said tube bankrespectively to said drum, longitudinally spaced rows of verticallydisposedfiuid conduit elements having their lower ends connected to thelower end of said tube bank and their upper ends to said drum, meansassociated with said elements forming bafiies dividing the space definedby said tube bank, circulator tube rows and drum into a plurality oi-gaspasses including a pair or wide and narrow upflow passes and a laterallyadjoining downflow pass serially connected to said upflow passes attheir upper ends, a bank or steam heating tubes extending across andconfined to said wide upflow pass, flow control damper means for saidnarrow upflow pass, a bank or multiple-looped economizer tubes in saidnarrow upfiow pass below said damper means with the tubes thereofarranged transversely of said steam generating tube bank, and aplurality of supporting tubes extending across said downfiow pass andsaid narrow upflow pass below and supporting said economizer tube bankand having their opposite ends connected to said drum.

'7. A steam generator comprising a setting enclosing a bank of inclinedsteam generating tubes, a steam and water drum arranged a substantialdistance above said tube bank, uptake and downtake circulator tubesconnecting the opposite ends or said tube bank to said drum,longitudinally spaced rows or, vertically disposed fiuid conduitelements having their lower ends connected to the lower end or said tubebank and their upper ends of said drum, means associated with saidelements forming bafiies dividing the space defined by said tube bank,circulator tube rows and drum into a plurality of gas passes including apair or upflow passes and a laterally adjoining downflow pass seriallyconnected to said upflow passes at their upper ends, a bank or steamheating tubes extending across and confined to one or said upfiowpasses, a sectional economizer comprising a tube bank extending acrossonly said downflow pass and a second tube bank extending across only theother upflow pass, flow control damper means for said other upflow passarranged above said second economizer tube bank, said economizer tubebanks being arranged with the tubes thereof extending transversely ofsaid steam generating tube bank, means for supporting the ends of saidfirst economizer tube bank at opposite sides of said setting. and aplurality of supporting tubes arranged below and supporting said secondeconomizer tube bank and having their opposite ends connected to saiddrum.

8. A steam generator comprising a setting enclosing a bank of inclinedsteam generating tubes, a steam and water drum arranged a substantialdistance above said tube bank, uptake and downtake circulator tubesconnecting the opposite ends of said tube bank to said drum,longitudinally spaced rows or vertically disposed fluid conduit elementshaving their lower ends connected to the lower end of said tube bank andtheir upper ends to said drum, means associated with said elementsforming baflies dividing the space defined by said tube bank, circulatortube rows and drum into a plurality of gas passes including a pair ofwide and narrow upflowpasses and a laterally adjoining downflow passserially connected to said upflow passes at their upper ends, a bank ofsteam heating tubes extending across and confined to said wide upflowpass, a sectional economizer comprising a tube bank extending acrosssaid downflow pass and a second tube bank extending across only saidnarrow upflow pass, flow control damper means for said narrow upflowpass arranged above said second economizer tube bank, said economizertube banks being arranged with the tubes thereof extending transverselyof said steam generating tube bank, means for supporting the ends ofsaid first economizer tube bank at opposite sides of said setting, abeam support centrally of said first economizer tube bank, and aplurality of supporting tubes extendin across said downflow pass andsaid narrow upflow pass below and supporting said second economizer tubebank and having their opposite ends connected to said drum.

9. In a steam generator comprising a setting enclosing a bank ofinclined steam generating tubes, a steam and water drum, rows of uptakeand downtake circulator tubes connecting the opposite ends of said tubebank to said drum, baffle means dividing the space defined by said tubebank, circulator tube rows and drum into a plurality of gas passesincluding an upflow pass and a laterally adjoining downflow passserially connected to said upflow pass at their upper ends, a bank ofsteam heating tubes extending across said upflow pass, and a bank ofhorizontally ar-' ranged multiple-looped economizer tubes arranged insaid downflow pass transversely of said steain generating tube bank andcirculator tube rows with their looped portions within said downflowpass, the improvement which comprises means for slideably supporting thelooped portions of said economizer tube bank from said setting atopposite sides of said setting and independently' of said circulatortubes, and a beam support arranged centrally below said economizer tubebank.

10. In a steam generator comprising a setting enclosing a bank ofinclined steam generatingtubes, a steam and water drum, rows of uptakeand downtake circulator tubes connecting the opposite ends of said tubebank to said drum, baflie means dividing the space defined by said tubebank, circulator tube rows and drum into a plurality 01 gas passesincluding an upflow pass and a laterally adjoining downflow passserially connected to said upflow pass at their upperends,

most economizer tube bank, and means including rigid tubular connectorsproviding a flow connection between corresponding tubes of said econo- Prt. I

a bank of steam heating tubes extending across said downflow passtransversely of said steam generating tube bank, the improvement whichcomprises a center beam support'ior the lower- 11. In a steam generatorcomprising a setting enclosing a bank of inclined steam generatingtubes, a steam and water drum, rows 01 uptake and downtake circulatortubes connecting the opposite ends o'fsaidtube bank to said drum, bafliemeans dividing the space defined by said tube bank, circulator tube rowsand drum into a plurality of gas passes including an upflow pass and alaterally adjoining downflow pass serially connected to said upflow passat their upper ends, a bank of steam heating tubes extending across saidupflow pass, and a plurality of vertically spaced serially connectedbanks of multiplelooped economizer tubes arranged in said downflow passtransversely of said steam. generating tube bank, the improvement whichcomprises means for supporting said economizer tube banks at oppositesides of said setting, a center beam support for the lowermosteconomizer tube bank, and means including rigid tubular connectorsproviding a flow connection between corresponding tubes of saideconomizer tube banks arranged to transmit the center load of an uppereconomizer tube bank to said lowermost economizer tube bank and beamsupport.

12. In a fluid heater comprising a setting enclosing a pass for thepassage of heating gases, a plurality of vertically spaced seriallyconnected banks of multiple-looped fluid heating tubes horizontallyarranged in said pass, a center beam support for the lowermost tubebank, and means including rigid tubular connectors providing a flowconnection between corresponding tubes of vertically adjacent tube banksarranged to transmit the center load of an upper bank to said lowermostbank and beam support.

13. In a fluid heater comprising a setting en-' closing a pass forthepassage of heating gases, a plurality of vertically spaced seriallyconnected banks of multiple-looped fluid heating tubes horizontallyarranged in said pass with substantially all of their looped portionswithin said pass,

means for slidably supporting the looped portions of said tube banks atopposite sides of said setting, a center beam support for the lowermosttube bank, and means including rigid tubular connectors providing a flowconnection between corresponding tubes or vertically adjacent tube banksarranged to transmit the center load of an upper bank to said lowermostbank and beam support.

DANA H. N. MAYO.

ARTHUR E. RAYNOR.

